1. Field of the Invention
The present disclosure pertains to searching a geographic database, and more particularly to using a grid of cells to identify bounds of a search of the geographic database, with certain of the cells identified as cells nearest to a central point of the search.
2. Description of the Prior Art
Geographic databases exist, which identify geographic, or mapping, information coupled with geographic objects, such as points of interest (POIs), each of is identified in the geographic database using associated information including geographic location information and other attribute information. Other information that may be stored for a POI includes, but is not limited to, name, POI type (e.g., city hall, police station, gas station, park, restaurant, etc.) More and more, people are relying on a geographic database, and are using applications that access a geographic database, to locate a POI based on the geographic information associated with the POI. Such applications include navigation systems used in telephones and other handheld devices, desktop computer applications, in automobiles and other vehicles, to name just a few.
Typically, an application requests information from a geographic database, such as POIs and information associated with POIs, based on some criteria specified by the application itself or a user. The criteria is used to query the database, retrieve a set of search results, e.g., POIs, that satisfy the criteria, and in some cases filter the search results before they are returned to the application. A request for information typically identifies at least an initial geographic location and some information to limit the search, such as a distance from the initial geographic location.
The information provided by an application typically identifies a central location for the search and a distance from the central location, which information can be used to define an area for the search. In a conventional approach, the center point and distance are used to define a search area, with the distance typically being used to identify a radius, r1, of the circular area. If the first search fails to yield the desired results, a second search expands the area using a second radius, r2, which is larger than r1, and the original center point. However, the second search includes the area of the first search, which results most if not all of the first search area being included in the search area for the second search.